Various techniques have been developed to avoid uneven baking in a high frequency heating device which heats an object to be heated such as food by providing high frequency power to a surface wave transmission line using a periodic structure.
For example, Patent Literature 1 discloses a high frequency thawing and heating device which supplies a microwave from two microwave supply ports formed on a surface wave transmission line so as to face each other. According to Patent Literature 1, a surface wave is evenly formed in an entire region of the surface wave transmission line.
Patent Literature 2 discloses a microwave processing device provided with a plurality of surface wave transmission lines and a plurality of power feeding units. In the microwave processing device, each connection position between the two adjacent surface wave transmission lines and the power feeding unit is disposed so as to be shifted in a microwave transmission direction. According to Patent Literature 2, cooking with less uneven baking is performed.